温度对青虾胚胎及幼体发育影响的初步观察

１材料和方法１．１育苗场条件育苗在岳阳市水产研究所原河蟹育苗厂房进行，厂房为玻璃屋顶，育苗池为水泥池，共１０个，每个面积３０米２，深１．５米。育苗用水取自芭蕉湖，水质清新，无污染。育苗池不铺设气石，采用鼓风机充气增氧，使育苗池水的溶氧量在５毫克／升以上，并形成一定的波浪。１．２亲虾培育及孵化亲虾从洞庭湖捕捞，个体重为０．２～０．３克／尾，长４～５厘米。先将亲虾放入暂养池中交配抱卵，已抱卵的亲虾移入育苗池中培育，待孵出蚤状幼体并达到一定密度时，用虾笼将亲虾诱捕出池。为保证每池排放的蚤状幼体发育同步…     

罗氏沼虾养成中白体病防治措施

１．购买虾苗时应检查有无白体病，有病虾苗不要买，同时虾苗入池前应消毒，用０．４×１０－６浓度溴氯海因全池泼洒，３～５天后再用活性微生态制剂按１．５×１０－６浓度全池泼洒，调节水质，抑制有害微生物生长繁殖。２．平时每月用一次溴氯海因０．４×１０－６浓度全池泼洒，每月使用一次虾宁２％按饵料量或虾菌宁５‰按饵料量或虾康宁６‰按饵料量一次，连用３天。３．治疗方法：第一天用溴氯海因０．５×１０－６浓度或二溴海因０．３×１０－６～０．５×１０－６浓度全池泼洒，第二至第六天内服虾宁４％＋虾菌宁５‰…     

泰国生态养虾情况的考察报告

１泰国养虾业的基本情况１．１淡水养虾品种以罗氏沼虾和斑节对虾（虎虾）为主。罗氏沼虾曾是泰国淡水养殖的主要品种,从８０年代初开始迅速发展,产量很大,不仅在国内很有市场,同时也是重要的出口品种,创汇率很高。但最近几年内陆虾农更加青睐斑节对虾,它经过品种淡化,可在咸淡水中生长,而且个体大、生长快,肉味鲜美,营养丰富,经济价值高。一位虾农介绍说,他已经有近１０年的淡水养虾经验,虾池一般为４徕（约９．６亩）１个,每池每茬放养１ｃｍ左右的普通虾苗４０万尾（平均每亩４万尾）,盐度２～５,水深０．７～１．５ｍ。…     

塑料薄膜大棚培育青虾苗的试验

本试验用塑料大棚培育青虾苗，经１个多月培育，不仅亲虾产卵率比对照池高，６月２５日出苗时，试验池１．２１厘米以上的虾苗占７１．４％，而对照池只占４．２％，１１月２５日起捕测量，试验池４．５厘米以上的虾苗占７９．４％，而对照池３０．６５，塑料薄膜大棚培育青虾苗对提高青虾当年上市规格有很大作用。     

罗氏沼虾人工孵化育苗试验

采用自育自繁亲虾，用温泉水高温，人工育苗１８．５９万尾（０．８－１．０ｃｍ），最高育苗密度１０．３万尾／ｍ＾３，成活率８４．５％；外购亲虾用锅炉提温，人工育苗７．７９万尾（１．６５ｃｍ），育苗密度５．５３万尾／ｍ＾３，成活率６４．９８％，孵化育苗水温２６．０－３０．０℃、ＰＨ７－８．５、盐度１２－１４‰、溶氟４－６．５ｍｇ／ｌ，氨氮０．３－０．８ｍｇ／ｌ。本试验表明，罗氏沼虾人工孵化育苗，在辽宁地     

涝洼地养殖罗氏沼虾试验

在水库区和河滩涝洼地挖池试养罗氏沼虾,１９９６年试养８亩,１９９７年试养１０亩。采取清池肥水,池底设隐蔽物,投喂人工配饵,调控水质等措施,１９９６年共产罗氏沼虾４００ｋｇ,平均亩产５０ｋｇ,平均体长８．０ｃｍ,尾重１７．５ｇ,成活率３０．５％,饵料系数３．５：１９９７年共产虾５２５ｋｇ,平均亩产７５ｋｇ,平均体长８．５ｃｍ,尾重２０ｇ,存活率３５％饵料系数２．５。投入产出比分别为１：２．１和１：２     

广西地区南美白对虾淡化养殖技术介绍

南美白对虾适应盐度较广,能在海水里生长,也能在淡水中生长,但必须在海水中繁殖,适宜水温在１８℃－３５℃,１５℃以下停止生长。南美白对虾食性较杂,对饵料蛋白质要求较低,３５％左右即可。该虾白天具潜沙习性,目前该虾在我地淡水养殖已获成功,池塘养殖亩产达１５０公斤以上,水泥池养殖每平方米产量达１．１５公斤。该虾是海虾淡养的又一养殖品种。 一、养殖池塘的建造 养殖池塘选点要求水源充足、水质好、无污染、底质好、土质坚实、排灌方便。虾池面积在５－１０亩为宜,一般不超过２０亩,水深在１ｍ以上,最好在１．５－１．…     

青虾夏秋季高产养殖技术简介

青虾是江、浙、沪一带平常百姓餐桌上 常出现的佳肴,市场需求极大,每年６月底 至１１月份的夏秋季养殖是全年青虾养殖 关键时期。目前在很多地区,青虾养殖面积 大,但养虾风险仍较高,集中表现为：青虾 产量低,上市规格小。而我们通过几年的成 功养殖,夏秋季虾亩产达７５ｋｇ,并达到了较 大规格。现将养殖技术要点总结如下： 一、池塘要求。开挖新池长度不限,池 宽限制在２０－３０ｍ之间,最好以南北向为 好,池深１．８ｍ,水位可保持在１．２－１．５ｍ,坡 度１：３或１：４。新塘养殖在春季应以大量 猪、牛、羊粪育肥,再配合以…     

罗氏沼虾与鳜鱼轮养技术

罗氏沼虾不耐低温，水温降至１５℃时，需干池起捕上市，养殖池实际只利用半年。利用罗氏沼虾冬闲期养鳜鱼，此阶段苗种便宜，饵料鱼丰富，鳜鱼养至翌年４～５月份上市，价格相对较高。实行罗氏沼虾与鳜鱼轮养，最大限度地利用鱼池闲置期，提高池塘产出率，增加养殖效益。一、池塘条件与准备１－选择池塘要求池塘水源充足，灌注水方便，面积３～５亩，池塘滩脚平坦，坡比１∶３以上，有效保水深１－２～１－５米，放苗前，必须进行干塘、清整、曝晒，开挖宽１米、深０－５米且同排水沟相通的沟作为收虾槽；每亩用１００千克生石灰干法清塘，…     

红螯螯虾人工繁殖技术研究：II.红螯螯虾人工繁殖技术的探讨

红螯螯虾在厦门地区可以生长繁殖，其繁殖期为５－１０月份，盛期出现在６－８月份。每年自然水温上升至２６．３－２９．３℃时，受精卵孵化至稚虾需４２－４７天。用塑料编织网作为幼苗隐蔽栖息材料，投喂对虾苗在用１－２号配合饲料育效果理想。平均水温为２８℃时，由离开母体的稚虾（体长８ｍｍ）培育至体长为２－２．５ｃｍ的规格种苗，约需２５天。在正常情况下，每平方米育苗池，可生产出种苗１２３４－１９１０尾。     

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.     

Growth performance,digestive enzyme activity and immune response of Japanese sea bass,Lateolabrax japonicus fed with fructooligosaccharide

In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.     

Rare serotype occurrence and PFGE genotypic diversity of Streptococcus agalactiae isolated from tilapia in China

Previously, we reported 10 PEGE types of 85 tilapia Streptococcus agalactiae(GBS), which shifted from Streptococcus iniae in China, by using PEGE method. Presently, larger and more representative tilapia GBS were isolated, for the ?rst time in China, to characterize their serotypes and genetic diversities more precisely than had done before. 168 GBS strains were distributed in ?ve provinces of China, in which Guangdong, Guangxi and Hainan were the major ones, holding36.9%(62/168), 37.5%(63/168) and 19.6%(33/168), respectively. Serotypes, Ia, Ib and III, were observed in these strains and the most predominant one was Ia(95.2%), which mainly distributed in Guangdong, Guangxi and Hainan. Ia initially occurred in 2009, it shoot up to 32.1% in 2010,but decreased to 16.1% in 2011 before went up to 45.2% in 2012. Ib sporadically occurred during2007–2011, III onlyoccurred in 2012. 14 different PFGE types, including 4 new types(N, O,P and Q), were observed, in which B, D, F and G were the predominant types, holding 83.9%(141/168) of the total GBS strains. Ia corresponded to 11 PFGE types(A–H, N–P), in which type D predominated(51%). Ib represented 3 genotypes(I, J and Q) and III harbored only 2genotypes(N and F). Type N and Fsynchronously presented in Ia and III. In summary, the genetic diversity of tilapia GBS varied by serotypes and changed with geographical locations and years.Although Iastillpredominated, new rareserotypeIII alreadyoccurred in China.     

Growth hormone (GH) and reproduction: a review

Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations.     

Purification and partial characterization of GtHs (cfLH and cfFSH) from Indian walking catfish (Clarias batrachus) (L.) and development of a homologous ELISA for cfLH

Two gonadotropins (GtH; Qa and Qb) were purified by gel filtration and ion exchange chromatography from the pituitaries of Indian walking catfish (Clarias batrachus). The presence of GtH during purification was assessed by in vitro oocyte maturation and in vivo steroidogenic activity, and their identities were determined by elution profiles, molecular weight, biological activities and yield. The molecular weights of Qa and Qb were 37 and 42 kDa, respectively, and composed of distinct subunits (Qa: 20 and 14 kDa and Qb: 26 and 18 kDa). Polyclonal antibodies raised against Qa immunostained Qa, Qb and pituitary GtH cells. A competitive Qa‐ELISA was developed whose sensitivity was 6.25 ng mL^?1 (1.25 ng well^?1) with intra‐ (3.5%) and inter‐ (12.4%) assay coefficients of variation. Displacement curves parallel to the standard were obtained with plasma and pituitary extracts of catfish, Qb and carp GtHII. The assay was validated by measuring the plasma Qa levels after LHRH treatment and in relation to ovarian growth in the female catfish during different reproductive phases. Based on the results, Qa and Qb corresponded to fish LH and FSH respectively. The findings will increase the knowledge of the mechanisms controlling fish reproduction and identification of sensitive phases in fish in captivity for hormonal manipulation.     

Controlled infection of Poecilia reticulata Peters (guppy) with Tetrahymena by immersion and intraperitoneal injection

Tetrahymena is a protozoan parasite, which infects guppy, Poecilia reticulata Peters, and causes substantial economical losses in commercial farms worldwide. Studies of guppy infected by Tetrahymena require standardized infection protocols. The LD50 for Tetrahymena infection of guppies by intraperitoneal (IP) injection was calibrated, and the level obtained was 946 parasites per fish. Guppy infection with Tetrahymena by immersion, imitating the natural route of infection via the integument, was studied under normal or stress conditions. Exposure to cold and netting (CNI) and to cold only (CI) followed by immersion exposure to 10 000 Tetrahymena per mL resulted in 22.5% and 19.2% mortality, respectively, as compared to 14.2% and 10% in groups that were netted only (NI) or non‐stressed (I). Histopathology revealed that immersion infection resulted in a systemic infection. Lysozyme levels, measured 3 weeks after infection, were significantly higher in the CNI group (288 μg per mg protein) compared with CI‐, NI‐ and I‐treated groups (94.5, 64 and 62.3 μg mg^?1, respectively). There was no evident parasite immobilization activity in body homogenates, suggesting no development of acquired immunity. Re‐infection by IP injection revealed no increase in protection in any of the treatment groups, mortality range of 56.3–75%, higher than in the non‐exposed control (40.6% mortality).     

Involvement of gonadal steroids in final oocyte maturation of white perch (Morone americana) and white bass (M. chrysops): in vivo and in vitro studies

Plasma estradiol-17 (E₂), testosterone (T), 17,20-dihydroxy-4-pregnen-3-one (DHP) and 17,20,21-tri-hydroxy-4-pregnen-3-one (20-S) levels were measured by radioimmunoassay (RIA) in white perch (Morone americana) and white bass (M. chrysops) that were induced to undergo final oocyte maturation (FOM) with human chorionic gonadotropin (hCG). Plasma DHP levels increased in females of both species in association with oocyte germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD) and decreased thereafter. Plasma 20-S levels also increased with oocyte GVM in white bass, but were several-fold lower than DHP levels. Circulating E₂ and T levels were greatest during GVM and GVBD in both species and decreased to low levels during oocyte hydration and ovulation. Follicles from white perch and white bass which received a priming injection of hCG in vivo, produced both DHP and 20-S in vitro after exposure to hCG and their oocytes underwent GVBD. Ovarian incubates from unprimed fish of either species produced only E₂ and T and their oocytes did not complete GVBD. Oocytes from unprimed bass, but not perch, matured when follicles were exposed to hCG in vitro. Both trilostane and cycloheximide blocked in vitro production of DHP and 20-S and oocyte GVBD by white perch follices. DHP and 20-S were equipotent inducers of FOM in the GVBD bioassay. None of several other structurally-related steroids tested were effective within a physiological range of concentrations. These results indicate a role for DHP and 20-S in the control of FOM in white perch and white bass.     

Cardiac,ventilatory and metabolic responses of two ecologically dissimilar species of fish to waterborne cyanide

Changes in heart rate, ventilatory activity and oxygen consumption were determined in trout (Salmo gairdneri) and brown bullhead catfish (Ictalurus nebulosus) during exposure to a steadily increasing concentration of waterborne cyanide selected to produce death in 8–9 hours for each species. The lethal cyanide concentration for the bullheads was an order of magnitude higher than for trout. Trout developed an immediate and gradually increasing bradycardia throughout the exposure period. Cyanide produced tachycardia in the bullhead followed by a gradual onset of bradycardia as the concentration of cyanide was raised. Pericardial injection of atropine (a muscarinic cholinergic antagonist) indicated that bradycardia in the trout was due initially to increased vagal tone but later due to the direct effect of cyanide on the heart. Hyperventilation in the trout persisted throughout the exposure period, although the rate and amplitude fluctuated and was variable between individual fish. During the last hour of exposure (highest cyanide concentration), ventilation was characterized by rapid, shallow breaths followed by a sudden respiratory arrest. The bullheads exhibited hyperventilation during the first 3 hours of exposure followed by a gradual, linear drop in ventilation rate and amplitude until death occurred. Cardiac and ventilatory responses in both species were attributed to stimulation of central and peripheral chemoreceptors by cyanide. Evidence is presented which suggests the initial response in the bullheads was due, at least in part, to gustatory stimulation by the cyanide. Oxygen consumption of the trout remained above pre-exposure levels for the majority of the test period. Oxygen consumption in the bullhead paralleled the changes in heart and ventilatory rates. Whole-body lactate levels of fingerlings of both species during cyanide exposure were measured to estimate the extent of anaerobiosis. Whole-body lactate levels were much greater in the bullheads than the trout, indicating a higher capacity for anaerobiosis, possibly due to a greater fuel supply. Overall, the trout responded to cyanide in a manner similar to that produced by environmental hypoxia whereas the bullheads experienced a gustatory stimulus which masked the hypoxia-like response.     

An overview of stress physiology of fish transport: changes in water quality as a function of transport duration

This study brings an integrated analysis about the relationship between water deterioration and its physiological consequences in live fish transport. The analysis was focused on the transport water and its deterioration, and physiological challenges imposed on the fish. Usual commercial handling procedures employed to mitigate fish stress during transport were discussed. Future topics of research for the establishment of safer fish transport protocols were proposed. Transport was classified into short (≤8 h) or long transport (>8 h). The main issue in short transports should be the prevention of water pH reduction, while in long transports it is the increase in ammonia. Plasma cortisol is the most employed marker for stress and is acutely elevated upon short episodes of transport, but remains elevated even in long‐transport events. Plasma glucose is perhaps a better marker for handling stress. Plasma lactate, pH, osmolality CO₂ and ions should be more often evaluated. Plasma Na⁺ and Cl^‐ are very useful markers of acidosis, due to their respective exchange for H⁺ and , for acid–base regulation. The establishment of species‐specific transport protocols should be preceded by such combined analyses of water and physiological parameters.